I'm having this strange problem with the newer versions of NW. It's very noticeable when the sprite or 9patch have transparent edges.Take a look at the difference between node versions with a rope that I made with some little white pieces:

No problem. That's with node 0.19.4 - http://imgur.com/a/jtM73

Problem. That's with node 0.21.1 - http://imgur.com/a/AS8cs

Seems like with the newer nodes the transparent edges are bigger, cause it's more visible. The rope looks "sliced".

I know that the aliasing can look different depending on the browser (I've experienced this sort of thing too). My guess is because they might be using different algorithms to handle certain rendering/transformation processes. Maybe someone more knowledgeable about it could give their take on it.